This invention relates generally to missile seekers which provide guidance information to direct a missile toward a desired target. More particularly, the invention relates to a dual mode missile seeker responsive to either infrared radiation or radio frequency energy from a target to guide a missile to such target.
Manned aircraft have been, and will continue to be, one of the principal means of weapons delivery in modern warfare. Manned aircraft combine accurate delivery of projectiles with the capability of reconnaissance and surveillance and can utilize the intelligence of airborne observers within the aircraft for location and identification of ground targets. Improved radar processing techniques such as synthetic aperture mapping can provide aircraft the capability of attacking ground targets under adverse weather conditions and at night. If allowed to roam freely in the airspace over the battlefield, aircraft can be the decisive factor in the ground engagement.
To counter this threat, highly effective ground-based antiaircraft defenses are being developed and deployed to reduce the probability of aircraft penetration of battle areas to such levels that sustained use of aircraft becomes impractical. These defense systems have one thing in common: They all use some form of radiation such as radar for search, acquisition, tracking or fire control. The radiation from the aforementioned defense systems may lie at any frequency within a large frequency band available to radar devices, and said radiation may have one of several polarization senses. A missile seeker designed to home in on such radiation, sometimes hereinafter referred to as an antiradiation missile (ARM) seeker, must therefore be capable of operating over greater than an octave band of frequencies and must be responsive to any one of several polarization senses.
To counteract the effectiveness of ground defense systems employing radar guided missiles against attacking aircraft, or to avoid detection by such ground defense systems, attacking aircraft may employ high power jamming signals to neutralize the ground defense radar. Anti-radiation missiles can attack such jamming aircraft providing that they continuously transmit jamming signals. If, however, sensing that they are under attack, the jamming aircraft cease transmitting, then the anti-radiation missile becomes ineffective unless it has an alternate guidance mechanism. Such alternate guidance mechanism must, however, ensure that the target may be acquired while the tracking loop of the seeker of the antiradiation missile is closed through the R.F. receiver.